Nearly a month after an international student at the University of Illinois went missing, FBI officers arrested a suspect who they believe abducted the young woman and held her against her will.

The officials also believe the victim might not be alive anymore.

The FBI arrested Champaign resident Brendt Christensen for allegedly kidnapping Yingying Zhang, who graduated last year from Beijing's Peking University with a master's degree in environmental engineering and arrived at the university in April to study photosynthesis and crop productivity.

The 26-year-old woman was serving a yearlong position at the school’s Department Of Natural Resources And Environmental Sciences and had been on her way to sign an apartment lease when she went missing on June 9, according to the FBI.

The 28-year-old suspect is also a former University of Illinois physics graduate who received his master's degree in May. He also worked as a teaching and research assistant for four several semesters, but it is unclear if his path ever crossed with Zhang during the short time she was there.

A search of his phone also revealed he visited threads titled “Abduction 101,” “perfect abduction fantasy” and “planning a kidnapping” on the website FetLife.

The victim was originally from Nanping, a small city in southeast China. Her father, boyfriend and aunt came all the way from their home to Illinois during the search.

How did it happen?

The day she disappeared, Zhang was reportedly heading to an apartment complex in Urbana to speak to the manager of a building where she was planning to lease an apartment. They were supposed to meet at 2 p.m., but she texted the building manager around 1:39 p.m. to say she would be 10 minutes late.

The surveillance footage obtained by the authorities showed Zhang boarding a Champaign-Urbana Mass Transit District bus around 1:35 p.m. At around 1:56, she tried to flag down another bus, but it did not stop, according to the affidavit. The officials believe the bus probably did not stop because Zhang was standing on the wrong side of the street.

After missing her ride, Zhang walked to another intersection to catch another bus. The video showed her waiting on the designated bus stop when a black Saturn Astra, which appeared to be circling the area around the victim, pulled off to the side of the road. Zhang was seen speaking with the driver for about a minute before getting into the passenger seat. The car then continued driving north on Goodwin Avenue, said the authorities.

That was the last anyone saw of Zhang.

The building manager sent her a text at 2:38 p.m. to ask if she planned to come. However, he got no response.

Of the 18 four-door Saturn Astras registered in Champaign County, one belongs to Christensen. When officers went to his house and asked him of his whereabouts on June 9, he could not remember when he had been. He later told police he was either sleeping or playing video games all day.

The police did not find anything suspicious at first. However, they later noticed how the Astra caught on video had a sunroof and a cracked hubcap on the front passenger side — just like the one parked outside Christensen’s home. The investigators also discovered the front passenger side “appeared to have been cleaned to a more diligent extent than the other vehicle doors.”

The FBI agents then began monitoring Christensen. On June 29, he was overheard discussing how he kidnapped Zhang and held her in his apartment against her will. It is unclear who he was speaking to, but it was from this conversation the police deducted Zhang was no longer alive.

A day before his arrest, the suspect also allegedly attended a rally held to show support with Zhang’s friends and family.

The suspect also had an OkCupid account where he described himself as “pretty chill and easy going."

“It’s pretty much impossible to make me mad. I want to experience everything and test my limits,” he wrote. “I also work out a ton but don’t mind if you don’t. Fitness has been a passion of mine since junior high.”

He was apparently married as well.

“He would nearly always come with a woman; I don’t know if she was his wife or his sister,” Jon Bowman, who was part of the same workout group as Christensen, said of the suspect. “Most of us who were working out were usually talkative and in a good mood, but Christensen was different. He and the woman always wore black, and they kept to themselves. They never said anything to the rest of us.”

“Nothing indicated anything like this. It's just stunning,” said UI physics professor Lance Cooper. “Every email that I've gotten has been conveying utter shock. This is something that caught everybody off guard, particularly because we've all been following this story.”

It is also unclear if the authorities have recovered Zhang’s body.

“This is a senseless and devastating loss of a promising young woman and a member of our community,” Illinois Chancellor Robert Jones said in a statement. “There is nothing we can do to ease the sadness or grief for her family and friends, but we can and we will come together to support them in any way we can in these difficult days ahead.”

Jones reportedly also notified university staff and students of Christensen’s arrest and of law enforcement's belief that Zhang is no longer alive.

“I ask all of you to help to ensure that Yingying is remembered for her kindness, her gentleness and her smile,” he added.

The students were also planning to hold a ceremony in memory of Zhang. However, the school officials cancelled the event the victim’s father and aunt asked for privacy.

“Out of respect for their needs and in accordance with their wishes, we will not be holding a campus wide memorial today,” the university said.

There are around 5,600 Chinese students enrolled at University of Illinois and this tragic incident has spread concern among many.